Shared Element Transition In Jetpack Navigation From Recyclerview To Detail Fragment

I'm trying to make a transition with simple animation of shared element between Fragments. In the first fragment I have elements in RecyclerView, in second - exactly the same eleme

Solution 1:

Okay, I found that how should it looks like to have enter animation with shared element: In DetailFragment (Target) you should run postponeEnterTransition() on start onViewCreated (my code from onCreateView can be moved to onViewCreated). Now you have time to sign target view element with transitionName. After you end with loading data and view, you HAVE TO run startPostponedEnterTransition(). If you don't do it, ui would freeze, so you can't do time consuming operations between postponeEnterTransition and startPostponedEnterTransition.

Anyway, now the problem is with return transition. Because of course it's the same situation - you have to reload recyclerView before you release animation. Of course you can also use postponeEnterTransition (even if it's return transition). In my case, I have list wrapped by LiveData. In source fragment lifecycle observer is checking data. There is another challenge - how to determine if data is loaded. Theoretically with recyclerView you can use helpful inline function:

inlinefun<T : View> T.afterMeasure(crossinline f: T.() -> Unit) {
viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
    overridefunonGlobalLayout() {
        if (measuredWidth > 0 && measuredHeight > 0) {
            viewTreeObserver.removeOnGlobalLayoutListener(this)
            f()
        }
    }
})

}

...and in code where you are applying your layout manager and adapter you can use it like this:

recyclerView.afterMeasure { startPostponedEnterTransition() }

it should do the work with determine time when return animation should start (you have to be sure if transitionNames are correct in recyclerView items so transition can have target view item)

Solution 2:

From the answer that using ViewTreeObserver is quite consume resources a lot. and also have a lot of processes to do. so I do suggest you use doOnPreDraw instead of waiting after recyclerView was measured. the code implement will like this below.

recyclerView.doOnPreDraw {
    startPostponedEnterTransition()
}